Changes in Growth and Structure of Pea Primary Roots (Pisum sativum L. cv. Alaska) as a Result of Sudden Flooding

Abstract

Pea (Pisum sativum L. cv. Alaska) primary roots were exposed to flooding after growth for 4 or 5 d at 25 degrees C under relatively dry conditions. Flooding after 4 d growth reduced, but did not stop, primary root growth, and cavities caused by degradation of central vascular cells were typically found from 10-60 mm from the tips. Flooding after 5 d stopped primary root growth and caused cell death in the tips, and vascular cavities formed that typically were 20-60 mm from the tips of the roots. Degradation of root tip cells in 5-day-roots was very rapid and began in the elongation zone and later in the apical zone. Root tips discolored, narrowed or curled before growth arrest. The mitotic indices of 5-day-root tips were suppressed by the flooding treatment. A few mitotic figures were observed in roots treated with flooding after 4 d growth. Affected cells had condensed nuclei, but cytoplasms appeared to be normal in the early stages of cell degradation. Later these cells became very vacuolated. The relationship of flooding to root growth, vascular cavity formation, and the morphology of pea primary roots is described with regard to the ability to resist flooding stress.

Comparison of the effects of flooding vs. low-oxygen gas on pea (Pisum sativum L. cv. 'Alaska') primary roots

“…When pea seeds were germinated and grown in control conditions, cavity formation did occasionally occur as reported previously (Gladish and Niki, 2000;Niki and Gladish, 2001). But these cavities were 15-16 normal-looking roots were sampled at random from 23-24 roots per grown per beaker or growth tube.…”

“…In continuous warm conditions, VC in pea primary roots are relatively narrow (Niki and Gladish 2001), and the frequency of VC occurrence in seedling populations varies 20 to 100%, depending positively on the degree of saturation of the growth medium (Gladish and Niki 2000). There is some circumstantial evidence that large VC induced by sudden flooding in primary roots of pea (Pisum sativum) may serve as a kind of inducible aerenchyma (Niki and Gladish 2001, Gladish et al 2006, Gladish and Niki 2008. Natural soils usually have very complex and sometimes heterogenous composition and structure (Ponnamperuma 1984;Kalita 1999).…”

Cadmium- and Flood-Induced Anoxia Stress in Pea Roots Measured by Electrical Impedance

“…Additionally, sudden fl ooding induces the growth of vacuoles, which are also part of the electrical conductor system of the cells, and this can also contribute to decreased resistance and capacitance values (Niki and Gladish, 2001). Tissue impedance is closely related to both cellular ionic mobility (Vozáry et al, 1999) and the diameter of electrical conductors.…”

“…Flood excludes air from soil causing anoxic conditions (i.e. total lack of soil oxygen), and plant respiration switches from aerobic to anaerobic, creating ineffi cient energy supply, which fi nally leads to nutrient defi ciencies (Niki and Gladish, 2001).…”

Root Anatomical Responses to Waterlogging at Seedling Stage of Three Cordage Fiber Crops

“…10 cm in diameter and 19.5 cm tall) that contains ca. 1000 ml of vermiculite with 40% v/v (control) and 80% v/v (waterlogging) water contents (Niki and Gladish, 2001). The beakers were covered with aluminum foil and sterilized by autoclave at 120 o C for 90 min.…”